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Sherline Linux (Ubuntu) Version 5.0 with EMC2, updated 09/14/12

Operating Instructions for the Sherline

Vertical Milling Machine CNC System

P/N 8540/8541, 8020/8021, 8600/8601, 8620/8621

PRECAUTIONS1. Do not connect or disconnect stepper motors when the driver box is

powered up. Always turn off power to the driver box before plugging

unplugging a stepper motor. Improperly connecting or disconnecting

a motor can damage it.

2. Before turning on the computer and booting up EMC2, make sure thepower switch for the stepper motors on the side of the computer (or on

the 8760 driver box) is in the OFF position. After EMC2 is fully

loaded it is then OK to turn on power to the stepper motors. Controls

within EMC2 prevent overloading of the power supply when multiple

motors are powered up at the same time, but without this safeguard

motors or drivers can be damaged.

3. Before turning the computer on for the first time, confirm the 115/230Volt power switch on the back of the computer is in the correct

position. If it must be changed, note that there is a second power

selection switch inside the computer case on the driver board power

supply that must also be changed. Contact Sherline before removing

the tamper-proof label to open the case or you may void the warranty.

(The spindle motor will automatically adapt to any current from 100

to 240 VAC, so no transformer or switching is needed for it.)

4. If all stepper motors stop running at the same time, turn off power tothe stepper motors (switch on side of computer or back of 8760 driverbox), wait a few seconds and turn power back on. A protection circuit

was introduced on later model boards that will shut down power to

the stepper motors in case of an electrical surge or anomaly. Turning

power off and back on should reset the circuit.

SHERLINE PRODUCTS INC 3235 Executive Ridge Vista CA 92081-8527Tel: (760) 727-5857 or (800) 541-0735 Fax: (760) 727-7857E-mail: [email protected] Website: www.sherline.com

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NOTE: Effective January 2009, Sherline computers no longer come with a floppydrive. A USB flash drive is included instead to facilitate file transfers.

Finding the most current instructions

The most up-to-date version of these instructions can always be found on the Sherlinewebsite at www.sherline.com/CNCinstructions.htm. The following instructions refer tosystems utilizing the Ubuntu version of Linux and the EMC2 G-code control program.Older instructions for using the Debian version of Linux 4.xx and the EMC distributed bySherline starting January1, 2005 or the initial versions of 2.xx Redhat Linux will remainposted there as well.

Why we switched to Ubuntu and EMC2

The Debian version of Linux along with the EMC (Enhanced Machine Controller)software has been distributed by Sherline since January, 2005. It is thoroughly debuggedand stable, and if you only use a mill, it will still work fine. We have decided to offer theUbuntu version of Linux primarily because it now supports a broader range of hardware.Its interface will also be a little more comfortable for those familiar with Windows XP.

For example, you now double-click on files to open them instead of single clicking andthere is no longer a mount and unmount command for using a USB flash drive ordisc drive. Just click on the icon and it opens as it would in Windows. Small differencesaside, it also allows us to upgrade from EMC to EMC2. The graphic interface of EMC2again looks very much like the original EMC, but now includes a lathe-specific programin addition to the mill program. It also supports several additional G- and M-codes. Wefeel these advances make it worthwhile for us to change over, and we think you willappreciate the additional features as well. As before, the operating system and controlprogram are provided free of charge to Sherline CNC users.

CNC for Lathe Users

Purchasers of Sherline CNC lathe systems can also use these instructions, as the basics ofCNC apply regardless of the machine being run. Keep in mind that lathe operations willrequire somewhat different g-code simply because of the way parts are made on a lathe.While primarily written for the mill user, the instructions on how to write G-code aremore or less universal and can be applied to a lathe or a mill, keeping in mind the wayeach machine works. More specific instructions on the use of EMC2 and also the latheportion of the program can be found in the EMC2 user manual. A copy of the manual ispart of the software pre-loaded onto your Sherline CNC computer and can be found underthe main menu atApplications>CNC>EMC2 User Manual. It is also available on-line athttp://linuxcnc.org/docs/EMC2_User_Manual.pdf.

Use of non-Sherline Programs

Sherline cannot be responsible for the support of software or hardware products notdesigned or sold by Sherline. For questions on Windows CAD, CAD/CAM, control orfree utility programs, please contact the provider of the software. It would be impossiblefor Sherline to guarantee that G-code generated by any particular CAD/CAM programwill run on EMC or EMC2 without modification. A thorough knowledge of G-codeprogramming will always be useful to eliminate problems caused by post processors.
http://www.sherline.com/CNCinstructions.htmhttp://linuxcnc.org/docs/EMC2_User_Manual.pdfhttp://linuxcnc.org/docs/EMC2_User_Manual.pdfhttp://www.sherline.com/CNCinstructions.htm

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Safety Rules for Power Tools

1. Know your power toolRead the owners manual carefully. Learn its application andlimitations as well as the specific potential hazards peculiar to this tool.

2. Ground all toolsIf a tool is equipped with a three-prong plug, it should be plugged

into a three-hole receptacle. If an adapter is used to accommodate a two-prong receptacle,the adapter wire must be attached to a KNOWN GROUND. Never remove the thirdprong.

3. Keep guards in placeand in working order.

4. Remove adjusting keys and wrenchesForm a habit of checking to see that keysand adjusting wrenches are removed from the tool before turning on any machine.

5. Keep work area clearCluttered areas and benches invite accidents.

6. Avoid a dangerous work environmentDo not use power tools in damp or wetlocations. Keep your work area well illuminated.

7. Keep children awayAll visitors should be kept a safe distance from the work area.

8. Make your workshop kid-proofwith padlocks, master switches or by removingstarter keys.

9. Do not force a toolDo not force a tool or attachment to do a job for which it was notdesigned. Use the proper tool for the job.

10. Wear proper apparelAvoid loose clothing, neckties, gloves or jewelry that couldbecome caught in moving parts. Wear protective headgear to keep long hairstyles awayfrom moving parts.

11. Use safety glassesAlso use a face or dust mask if a cutting operation is dusty.

12. Secure the workUse clamps or a vise to hold work when practicable. It is saferthan using your hand and frees both hands to operate the tool.

13. Do not overreachKeep your proper footing and balance at all times.

14. Maintain tools in top conditionKeep tools sharp and clean for best and safestperformance. Follow instructions for lubrication and changing accessories.

15. Disconnect toolsUnplug tools before servicing and when changing accessoriessuch as blades, bits or cutters.

16. Avoid accidental startingMake sure the switch is OFF before plugging in apower cord.

17. Use only recommended accessoriesConsult the owners manual. Use of improperaccessories may be hazardous.

18. Turn the spindle by hand BEFORE switching on the motorThis ensures thatthe workpiece or chuck jaws will not hit the lathe bed, saddle or crosslide, and alsoensures that they clear the cutting tool.

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19. Check that all holding, locking and driving devices are tightenedAt the sametime, be careful not to over tighten these adjustments. They should be just tight enough todo the job. Overtightening may damage threads or warp parts, thereby reducing accuracyand effectiveness.

20. Dont use your lathe for grindingThe fine dust that results from the grinding

operation is extremely hard on bearings and other moving parts of your tool. For the samereason, if the lathe or any other precision tool is kept near an operating grinder, it shouldbe kept covered when not in use.

21. Dont let long, thin stock protrude from the back of the spindleLong, thin stockthat is unsupported and turned at high RPM can suddenly bend and whip around.

22. Wear your safety glassesForesight is better than NO SIGHT! The operation ofany power tool can result in foreign objects being thrown into the eyes, which can resultin severe eye damage. Always wear safety glasses or eye shields before commencingpower tool operation. We recommend a Wide Vision Safety Mask for use over spectaclesor standard safety glasses.

23.Checking/changing computer power supply voltage settingsSherline attempts toship each CNC computer set to the proper voltage for the customers country. Customersoutside the USA should check this setting to confirm it is correct before plugging in thecomputer for the first time. If you need to change the voltage setting, there are twoswitches. You must change both the 115V/230V power switch on the back of thecomputer and the switch on the side of the driver board power supply inside the computercase. For proper procedure, see Part I, System Components and Connectionsfurther on inthese instructions.

24.Static electricity can damage your computerIf the case must be opened, be sureyou are properly grounded before touching any components inside your computer. A

spark of static electricity can damage delicate circuits in some components in yourcomputer. Either wear an approved static electricity grounding strap around your wrist ortouch the case of the computer with one hand before touching any components with yourother hand.

25.Be sure you know what will happen BEFORE pushing the [START] buttonRun your program in [BACKPLOT] mode before running the actual part to make sure itwill run the path your are expecting. Make sure your machine is in the proper homeposition before starting the operation.

Electrical Connections

The power cord supplied is equipped with a 3-prong grounding plug that should be

connected only to a properly grounded receptacle for your safety. Should an electricalfailure occur in the motor, the grounded plug and receptacle will protect the user fromelectrical shock. If a properly grounded receptacle is not available, use a groundingadapter to adapt the 3-prong plug to a properly grounded receptacle by attaching thegrounding lead from the adapter to the receptacle cover screw.

NOTE:The electrical circuit designed into the spindle motor speed control of your latheor mill reads incoming current from 100 to 240 volts AC and 50 or 60 Hz and

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automatically adapts to supply the correct DC voltage to the motor. As long as you have aproperly wired, grounded connector cord for your source, the machine will operateanywhere in the world without a transformer. This has been true for all Sherline machinesbuilt since 1994.

STEPPER MOTOR CORDS:Do not disconnect the cable at the stepper motor endunless absolutely necessary. It is designed for limited use and can be easily damaged.When connecting and disconnecting the motors, always use the round plugs that connectto the driver box cables. Do not pull on the wiresto disconnect connectorsGrip theplugs themselves.

CAUTIONManual Adjustments Using the Handwheels

MANUAL MODE:A DC motor acts like a generator when cranked by hand. Whenusing the machine extensively in full manual mode it is recommended that you first turnoff the power supply to the motors and then physically disconnect the stepper motorsfrom the driver board cables to prevent the generated voltage from damaging components

on the board. Cover the ends of the motor connecting plugs with masking tape to protectthem from debris. When reconnecting, make sure the plugs are fully seated. Constantplugging and unplugging is not good for the connections, so avoid doing so unlessabsolutely necessary.

CNC MODE:When operating in CNC mode you do not need to disconnect the steppermotors when hand cranking slowly and over short distances to manually position theslides. The motors are locked up when power is on, so the power switch to the driversmust be in the OFF position. For longer positioning travels it is easier to use the JogMode and move to approximate position electronically. Final adjustment can then bemade with the handwheels (with power turned OFF). To keep from generating apotentially harmful back-current to the driver board, do not turn the handwheels

manually faster than about 1 rotation per second when the stepper motors are connectedto the driver board.

Lubrication

CNC machines require more attention to keeping the leadscrews properly lubricated thanmanual machines. When you crank the handles by hand you can quickly realize that aslide is going dry because you can sense the results of the extra drag. A CNC machinewill not complain and will always work with the instructions that you gave it. You tell itto run, and it will die trying to please you. The Y- and Z-axis screws can be easily oiled;

however, the X-axis screw needs special attention. You cant see it because it is locatedunder the mill table. The best way I have found to lubricate it is to move the mill table allthe way to the right, put some oil on your fingertips and transfer it to the leadscrew. Asthe table is moved back to the left, oil will find its way to the internal brass nuts.Remember, that any type oil is far better than none. The slides also require constantoiling. I believe these oiling procedures should be done after every four hours of

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operation. For more on lubrication see page 5 of the Sherline Miniature Machine ToolsAssembly and Instruction Guidethat came with your mill.

CNC System Warranty

If within one year from the date of purchase of a new Sherline CNC system any tool or

component fails due to a defect in material or workmanship, Sherline will repair orreplace it free of charge. In addition, it has always been our policy to replace at no cost allparts, regardless of age, which are determined to have been incorrectly manufactured orassembled and have failed due to this cause rather than because of improper use orexcessive wear caused by continuous use in a production environment. In cases such asthis, Sherline will inspect the machine or part and will be the sole judge of the merit ofthe claim.

Freight charges for returning a machine are not covered. Save the original packagingmaterial to use if the machine or computer must be returned to the factory for

service.Sherline will not participate in insurance claims where the sender didnt make anhonest effort to package the items to prevent damage caused by normal shipping stressesor repair said damage without charging the sender.

Merchandise that has been abused, misused, improperly maintained or insufficientlylubricated is not subject to warranty protection. Proof of date of purchase and dealername may be required for service under this warranty. NOTE: WD-40 is a rustpreventative, NOT a lubricant!

Specific exclusion for wear due to production use

Although many Sherline tools have found there way into production environments, theyhave been designed for intermittent use in home shops. It would be unreasonable toexpect a Sherline machine to stand up to the rigors of continuous production use.

Continuous use of stepper motor driven leadscrews in a production environment canintroduce wear that would be impossible to produce manually. Therefore, slides, gibs,leadscrews, leadscrew nuts and bearings that are subject to high wear due to continuoususage are not covered under this one-year warranty.

Non-warranty service and machine tune-ups

Sherline machines are easy to service, and all replacement parts are available from thefactory. However, if in the future you wish to return your machine for any reason to haveSherline repair or adjust it, we will be glad to do so. Our shop rates are very reasonableand our production people have all the proper tools and fixtures to repair or service yourmachine quickly and return it to factory new condition.

Returning machines or parts for warranty or non-warranty repairBefore returning any tools or parts for repair, please call first and obtain a ReturnMaterial Authorization (RMA) number so that we can process your order immediatelyupon receipt. Remove all non-essential parts from the machine to save shipping weightand return only the portion to be repaired. Wrap and package all parts securely so theycannot move around in shipment. We recommend that heavy parts be double-boxed.Include a brief written description of the desired repair and your return address and phone

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number or e-mail address inside the box so we can contact you if questions arise. Repairsare normally return-shipped the next workday after they are received.

Technical Support

If you have a physical or electrical problem with a machine, component or accessorymanufactured by Sherline, please feel free to contact us at 1-800-541-0735, 1-760-727-5857 or [email protected]. If you have technical questions regarding thefunctions Linux or EMC that are not answered in these instructions, the Linux groupmaintains an excellent website at www.linux.orgthat has a search function and a lot ofhelpful information. Remember that Sherline hasnt charged you a single penny for theSherline version of the EMC2 program even though we have spent a considerable amountof money and time adapting the software to the Sherline mill. Our CNC instructions alsoinclude a free basic course in the use of G-code, and the printed instruction manual thatcomes free with each machine is the most complete of its kind. Beyond that, werecognize that many of our customers are new to machining and to CNC, and we will doour best to put callers on the right track to the information they need to get their newCNC system up and running. Learning to use G-code and learning to cut metal beyondwhat we provide in our instruction manuals must ultimately be the responsibility of themachinist, but we will help where we can.

A short history of CNC

Ive been personally involved with CNC since the early seventies and soon realized thatthis was the way to make things. Back then all sorts of ideas were being tried to simplifythe mass production of machined parts. Many manufacturers were using hydraulic powerand came up with some interesting systems. The method of choice before NC (back thenthey were called Numerical Control (NC) because the storage device was a one inch widepaper tape) was a tracing system that duplicated parts by tracing them with a hydraulic

system controlled by a really neat valve controlled by a stylus that the operator wouldmove like a probe and the machine would duplicate their movements. Gigantic machineswere built around this idea for the aircraft industry.

Hydraulic CNC systems?

It was only natural that this was the group of manufacturers would be the first to try thisnew field, and did they ever come up with some weird systems. You also have to realizethat electronics were also pretty crude during that same time period. My first NC machinewas a Cinematic manufactured by Cincinnati machine tool. It had ball lead screws drivenby hydraulic motors and was fairly reliable and quite popular at the time. Tool changerswere still in their infancy. I ran it until it was so out-dated that I gave it away when it still

ran. Another interesting point is this machine had a wire wrapped control with fewcircuit boards. If a recent graduate of electronic engineering had ever looked into thecontrol enclosure, Im sure his first comment would be impossible.

I thought I bought a telephone company

My first machine that was controlled by electronics turned out to be a disaster. I bought itused and it had a stack of manuals 18 inches high. I never dreamed I was going to look atevery page but I did. When I opened the control and looked in there, I thought I bought a
mailto:[email protected]://www.linux.org/http://www.linux.org/mailto:[email protected]

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telephone company. I believe there were 120 individual circuit boards and thousands ofindividual transistors. It was manufactured by Edlund. We used to call it a Deadlund. Iwasted more time and money on that machine than I care to admit, and I felt relived as itwas loaded on a truck for its final journey to the junkyard.

Problems with no memory storage

The way this machine stored memory was interesting. At this time there werent anymemory storage devices invented for commercial use. What this control did was feed asingle block of code (a block of code contained the instructions the machine needed tomake a single move) into a very long piece of Ni-chrome wire. The high resistance of thewire would delay the signal long enough so the signal could be amplified at the other endand sent back on the same wire without interference. The signal would then bounce backand fourth until the machine had moved to a location that corresponded to that block ofcode.

Sometimes I can be persistently stupid

New machines were thousands of dollars more than I could afford and not that reliableeither. I remember a friend who had a three-year-old machine that cost over $100,000that needed service. The first thing the technician said was, I didnt think they had anyof these old bastards still running. You can imagine how my friend felt when he madethat $2500 payment each month.

Youd think I would have learned by then, but I can be persistently stupid at times. Mynext disaster was a MOOG milling machine. It used a Bridgeport base and didnt haveleadscrews. It was entirely controlled by hydraulics. Movement was controlled by thinplates that moved with the machine slides with accurate holes located at every inch. Pinsabout 0.187" (5 mm) would engage the proper hole and then another plate with holesspaced at 0.200" would come into play, and the last 0.200" relied on a single turn of a

lead screw. The machine finally arrived at a position within a 0.001" of accuracy. I didntrealize it when I bought it, but I was horrified to find that this mother worked like aplayer piano. The one-inch wide paper tape wasnt read with switching devices like othermachines. It actually was more like a valve that allowed or prevented air to get tocylinders that controlled hydraulic valves. When it read a block of tape (around 10 linesof holes of 8 holes each) the SOB sounded like a steam engine. I chalked that one off tohaving more balls than brains; however, we actually made more parts with it than we didwith theDeadlund.

It should also be noted that Im sure that these early NC machines were the best thatcould be designed with what was available, and the solutions that they came up with werequite ingenious at the time. Im looking back at it from a slightly humorous position and

in no way infer that the designers of that era werent up to the task. They just didnt havethe tools to work with that we do today.

The course is set

At this time, CNC machines could only cut straight paths, and as soon as the electronicswere available to store just a small amount of memory the new rage became look-aheadcontrol systems. This meant the cutting tools wouldnt create machining problems when

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they hesitated as the next block of information was read. Stepper motors were used for ashort period to drive the lead screws; however, within a few short years the entireindustry switched to DC motors. Encoders or resolvers were used to keep track ofposition. The DC motors controlled by fast computers and working in unison withaccurate ball lead screws created a system that was very close to where we are today;

however, they were slower and very expensive. Today, servo drives use AC motorscontrolled by varying the frequency to the windings, eliminating the brushes needed withDC motors. The latest innovation is linear motors that can move machine slides atincredible speeds.

A new way of thinking

The marvelous part of the CNC revolution wasnt just the fact that it was eliminatingworkers from sometimes very strenuous and boring jobs; it was that there was finally amethod of cranking these handles in unison to do things that the best machinist in theworld couldnt accomplish. By moving screws on the X- and Y-axes in unison, you couldmachine tapers, circles and, in fact, any shape you wanted. This allowed engineers todesign parts with the shapes that they wanted, not just shapes that were possible tomachine using the old methods. Machines that cost thousands of dollars suddenly becamescrap iron. These new CNC machines didnt care if they were cutting a complex shape ora straight line. Whether the tolerance was tight or not the machine was always right on,and the tools determined the tolerances.

Ball lead screwsthe missing ingredient

The lead screws used on these machines should be mentioned. They are the interfacebetween the computers and the mechanics. The problem of backlash was solved withball lead screws. These screws have re-circulating balls that roll in a groove groundinto a shaft at a pitch of two tenths of an inch. The pitch on these screws has increasedover the years to achieve speeds over 1000 inches (25 meters) per minute. At a pitch of

.200(5 mm), a lead screw would have to turn at 5000 RPM to accomplish this speed,which is why ball lead screws have as high as one inch in pitch. Even more amazing wasthe fact that they improved the accuracy as they increased the pitch. You can make a

.0001(.0025 mm) correction on a good CNC lathe. Think about that. A slide willaccelerate to a speed of over 1000 inches a minute in less than a second, move a shortdistance and decelerate, stop and still be accurate to one ten thousandth of an inch. Theball screws must be very precise, because a lead screw would be useless if it had anybacklash (the amount you have to rotate a lead screw before the slide moves).

Ball lead screws are very difficult to make, which makes them quite expensiveseveralthousand dollars for each axis. The people who solved the lead screw problem should be

commended as much as the electronic geniuses who came up with the computer controls.At Sherline, we have CNC machines that have been running over ten years and still donthave any noticeable backlash.

Carbide insert tooling changed the entire machine tool industry

At the same time, carbide insert tooling became available and took the market over like astorm. I dont think I could have ever convinced a machinist in the fifties that some day

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he would be taking 0.300" cuts on cold rolled steel at a cutting speed around 400 to 600fpm (200 meters/min) using a 40 hp lathe at 0.020" (.5 mm) feed rate for each revolutionwith little carbide tools made using powdered metal technology and held in place withlittle screws and still be able to get marvelous finishes on gummy old cold rolled at thesame time. They do, and we at Sherline do all these things that give our customers a lot of

bang for the buck. The consumers of products that manufacture using this technologybenefit as much as the manufactures that use them.

Because lathes could also produce these types of moves, the large and expensive formtools were on there way out. This may not seem significant, but by generating rather thanforming shapes, these shapes could be far more precise, and at the same time machinesdidnt have to be so massive to prevent tools from chattering. Hand scraped ways werereplaced by frictionless, ingenious slides that lasted for years with little maintenance.Because there is always the possibility of a crash, machines are no longer built where theheadstock is an integral part of the base casting, and in most cases they can be realignedif one of these disastrous events should happen.

Why I love CNC robots

In closing this section, I firmly believe that these machines that we call CNC are therobots of the future and I truly love them. They have allowed me, Joe Martin thedesigner, to design the parts that Ive always wanted to design without dumping myproblems on Joe Martin the machinist, who must produce parts for Joe Martin thebusinessman, who can supply you, the customer, a fairly priced quality product and at thesame time allow Joe Martin the owner a reasonable profit to buy more of these marvelousCNC machines, of course. And so it goes.

Even though this doesnt do the subject justice I thought you might find that interesting.Its always wise to see at least a brief history of a subject before becoming part of it, evenif its only statistical.

Here is something I wrote in my book thats available online that you may findinteresting. See http://sherline.com/business.htm.

THE NEW MANAGERS

CNC machines allow a smart worker to produce more work than ever. Rather thaneliminating the need for intelligent workers, these machines require organizationalskills that few managers have. The machines they control are very complex, andthe employees who can control these machines are equally as valuable to acompany as that of standard managers.In the past managers were consideredpeople managers. The managers who control these machines are robot managers.When you consider how important these machines have become to the quality andefficiency of manufacturing a product, the group of workers that controls thesemachines will soon be equal to the managing staff of any company in prestige andwages. Todays management still hasnt grasped this concept, but soon they willbe forced to accept this condition when they find their million dollar machinesoperating at half speed.
http://sherline.com/business.htmhttp://sherline.com/business.htm

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This CNC class is open to those willing to work hard

In order to make the following instructions more interesting for me to write and you toread Im approaching the teaching of CNC programming the same as I would as if I wereteaching a small class of students. The students who attend these specialized classes laterin life have various reasons and expectations for being there, and Im trying to address

the whole class as I write. When I take off on a tangent Im addressing individualstudents with a different background who I visualize sitting in the class and answering aquestion that I believe may be asked in a similar class, so please bear with me. I dontwant any of my students left behind.

Enjoy the flight

In many of the coming examples I also describe the movement of the spindle as anaircraft that youre riding in. This may seem far out there, but CNC milling is a 3Dworld, and if you try to describe these movements in the movement of the table slidesyoull soon not know whether you are coming or going. You have to visualize the workstaying still while the cutter moves. Again, bear with me and enjoy the flight.

A different way of learning

Long ago I became aware of the success rate of people who, when left alone with theirvideo recorder and an instruction manual, failed to pass the test and had to stay up late toturn on their recorder to record a show they wanted to save. From their own statistics youwould think manufacturers would have attempted to teach in a different manner, but theydont. The products get more complex, making the instructions more complex, and thepoor consumers of these products are at a loss. I dont teach using these methods becausethey obviously dont work. With my instruction you wont be sure if youre reading anovel or an instruction manual, but Im sure youll be able to program and make a partwhen you get to the end.

The first instructions I completely wrote for my tools (I had written instructions aboutradio control equipment and rules for RC events in the past) were how to cut a screwthread using a rather crude device I designed (but which works well) for a Sherline lathe.I was surprised how few calls on how to use it came in after I sold my first 200, becauseit is a bit of a complicated thing to do. I then started to wonder if anyone was using it, andyoull never know how relieved I was when a customer came in with a bunch of partsthat he made with threads on them.

I knew I was on to something and have always written in this style ever since because itworks. It had to work because at that time I was the only one at my company who couldanswer questions of this type, and I didnt have the time. The fact that Im a self taught

person probably has something to do with it. I even went on to write a couple of books inthis style that were well received.

A new challenge

I remember getting a call from Sears about my folksy style of writing that didnt followSears instruction guidelines about the screw cutting attachment. I asked him how manycalls they had received about how to cut threads using it. He answered, None. I asked

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him who there could answer a technical question of this type. He answered, Nobody. Isaid, With this being the case, dont you think you should leave well enough alone? Inever heard from him again. Right now, Im looking at these instructions as one of thebiggest challenges Ive ever taken on as an author, and I dont plan to fail. The averageinstruction manual written on this subject is two to three hundred pages of very technical

reading. Youll never crack a smile reading one of these manuals. Ill do it in less thanfifty.

The only students I hired who learned CNC had good teachers, not good trainingmanuals. In fact, I cant think of any employee in the last 30 years that Ive ever hiredwho learned CNC programming and how to run these complex machines on his own.You will! I had to learn on my own because I was so broke after I bought my first NC Iwas out of choices. I learned by staying up late, working my ass off and making costlymistakes. I would have given my left you-know-what if I had something like this to readrather than reading the junk written by professors trying to prove how smart they were toother professors rather than attempting to teach their own students.

Sherline customers want to build components

I saw the customer who was going to read these instructions as a person who wasn'tparticularly interested in computers or gadgets and was only interested in making parts. Ibelieved they were curious about CNC and wanted to learn about it without spending toomuch money. They probably haven't tried to learn how to do something this complicatedin the last 20 years. Remember that CNC is a new way of doing and thinking about themachining process, and I believe Ill help get your brain in tune with what you are aboutto learn with my ramblings.

Learning while you work

A student of this class could be already working at the trade. Words of advice for this

group: You cant afford to have idle thoughts as you load parts on machines that otherpeople set up and wrote the programs for unless you are satisfied to load parts for the restof your life.

First study the mechanical part of the setup; things like how the part is held and the typeof cutting tools used and how long they last. You have to show some initiative and startanalyzing the program you are running and ask intelligent questions. Notice, I saidintelligentquestions. Bosses are usually smarter than you think they are, and they easilyknow when some when clown is pulling their chain. Dont ever make suggestions unlessyou are sure you are right. A better way to make a suggestion of this type is to ask themjust why the job is set up or run the way it is rather than your way. That way youre notthreatening them with your question, and theyll appreciate a chance to teach you if you

are wrong. If you find out you were wrong, it gives you a way out by saying that youwere sure that they must have had a good reason. It wouldnt hurt to let that rule work itsway into your personal life.

When you start studying their programs, youll find them written like a story. Just like abook, the better the author, the easier the program is to read. Each tool used will have itsown chapter. (In the real world of machining youll run few machines without automatictool changers.) Study these chapters one at a time and watch what the machine does as

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the program advances. In case you didnt realize it, Im also instructing all you hobbyistout there on how to organize your programs and setups. Plan them like someone else isgoing to run the job and pick apart your own work. If you dont, you might find yourselftrying to machine your vise off the table.

Getting you into the learning mode

I also felt that people of this type would want to read something about what they are instore for before they started. I wanted my customers to understand just how difficult CNCprogramming can be to learn at the start and just how interesting it can be at the sametime. In other words, I felt Joe home machinist doesn't stand a chance unless he'sinspired to do so, and in my own way Im trying right now to inspire you to learn how toprogram and use these marvelous new CNC machines. I know how easy it is for you togo back to the way you already know or forget the whole idea. I don't want customerswho think it'll be easy to learn because they'll be unsatisfied from the beginning and takeout their anger on Sherline.

Youre about to learn how to control your robot

These aren't instruction about operating a simple single system like a VCR, butinstructions about controlling a very complicated device. You are not operators of thesemarvelous machines; you are masters telling your robot what to do, and you, thecontroller, have unlimited choices to make. I want to get this concept through to thataverage customer I mentioned, yet I know that only one out of five professionalmachinists I know seems to really understand this point.

Im going to be a student in my own class

I was shocked at just how much I had forgotten about the process of CNC programming.I probably know as much as anybody of what you can do with CNC machines, because Iown at least twenty modern machining centers, yet I havent really written any code in

fifteen years. After thinking about it for a couple of days while unsuccessfully attemptingto write a simple program I decided this is a good thing. I also decided that Id learn thisfrom the Linux site on my own and not use the books that were available to me. Ibelieved that if I wrote the instructions as I learned how to program EMC myself Idwrite better instructions; after all, all you have to be is one page ahead of your students toteach. Just joking, teachers.

Something for nothing

Sherline Products Inc. is not charging you for this EMC2 program, and it is free becauseof work done by NIST (National Institute of Science and Technology), a governmentfunded organization. The EMC (Enhanced Machine Controller) was written by the NIST

and is a very sophisticated program. We all now have the benefit of millions of dollars ofprogramming along with the source code, if needed, simply by asking.

We all owe thanks to the EMC group

At the time this program was written it was thought that only very advancedprogrammers and scientists would be using a program such as this, and the averageperson stood little chance of making it functional. Fortunately for us, a lot of very smart

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people before us, donating their time, started developing a programming interface thatallowed both businesses and hobbyists to take advantage of what they had done withoutbeing engineers. Im very pleased with what they have done. This group still workstogether through the Internet, and help is available through Internet chat groups. Manypeople have donated much of their time to make this system user friendly.

The EMC2 program operates under the Linux operating system, which is also a freesystem, and it would be wise to operate it from a dedicated computer for this task. A dualboot system can lead to problems, because Microsoft code has been purposely written tobe the dominant control of your computer whether you want it or not. I like the Linuxconcept of people working together where all have the benefit of any single personswork. For example, these instructions will have a Sherline link placed on the EMC for allto read whether they are Sherline customers or not. It will be my donation towards asuccessful system available to all. Im learning how to program EMC by using theinternet site put together by dedicated EMC users, so you can also fall back to their sitefor help. See http://www.linuxCNC.org/

This is going to be easy if you do it my way

The Linux operating system works pretty much like all the others. If you can find yourway around a Mac or Windows computer, you will have no trouble navigating menus,opening, closing and copying files or saving and deleting items in Linux. The newUbuntu version is the most Windows-like yet. When you turn on the computer, there willbe four icons on the desktop. Depending on whether you have a lathe or a mill, inch ormetric, choose the correct icon for your machine and double click on it. In a few secondsyoull get the graphical interface to the EMC2. Well, that was easy. Now, after BS-ingyou to death on how hard this was to do Im going to show you how easy this can be, butonly if you do it my way.

Computers have the patience of a saint

If youve had little computer experience, the first thing you will learn is that computershave the patience of a saint. If computers were more human they would probably like totoss their operators out the window as much as frustrated operators want to do the sameto them. The only way you can keep a computer from giving you an error message is tonot give it errors. The tricky part is computers dont always tell you the error to fix orhow to fix it. Computers just tell you that there is an error of a certain type. This canbecome maddening, and you have to know when to take a break and walk away. Thingsof this nature are the worst when, for the sake of your own sanity, they should be the best.In many ways, learning programming is similar to learning machining. You cant takeshort cuts. If you find yourself going in the wrong direction, back up immediately.

Learn machining first

If you know little about machining and little about computers Id suggest you firstconcentrate on learning about machining. How can you expect a machine tool and acomputer to carry out your commands if you dont know the commands to give? Aboveall, dont start with a project so complex you dont stand a chance in hell of succeeding.Let each simple problem solved have its own rewards in knowing you just traveledanother block further down the CNC machining super highway, route EMC.
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NOTE: I have written a book called Tabletop Machiningthat is an introduction tometalworking at the small end of the size scale. Details can be found atwww.sherline.com/bookplug.htm. If you are new to machining, you will find theinformation in this book quite helpful.

You will be learning the CNC language of the robot world

The standard G code method of programming is to simply replace the manual inputsinto a machine (cranking the handles) with the commands that have become industrystandards. This is the method you should learn before learning any other method ofprogramming. It is the basic way that CNC machines talk to other CNC machines.Even if a simpler system were available today I still wouldnt teach it. It would be similarto teaching a language that few citizens of the world spoke. Programs written using G-codes can be read throughout the world. G-code standards came about very early in thegame because this game was controlled by engineers rather that marketing people.

Contouring programsanother world

Programs that allow you to do contouring quickly become very complex. Today there aresome affordable programs available for sophisticated hobbyists. These programs cancreate as many problems as they solve, because of the complexity of each program. Eachprogram has to work with other programs, and each program has its own set of complexrules. If you think you can learn these programs easier than you can solve a couple of trigproblems youre in store for a rude awakening; however, if you already know how to use3D CAD programs you could quickly find these programs very useful. It should also bestated that it is the only way available to create contoured machined shapes.

What it costs in the industrial world

The basic method that these programs work together in the industrial world and the costof these programs is: 1) The part is designed using a modeling program ($5000 to

$10,000), 2) The modeling program is converted to a CNC program (another $5000 to$6,000) and 3) the resulting code is run on a CNC machine starting at ($25,000) thatmakes the part. The people who can operate these systems are carefully chosen, trainedand well paid. The fact is that any business has no choice except to use the program theypurchased, because the programs cost so much and are so very necessary to remaincompetitive in todays world. They have to spend a great deal of money to accomplishthis, while the hobbyist has a choice.

Todays low-cost programs were once complex, expensive programs

The business world understands how complex it is to implement these procedures; thehobbyist doesnt. Because the hobbyist may be purchasing a program that cost thousands

of dollars just a few short years ago for a few hundred dollars, the programs themselveshavent become less complicated. They only cost less! In your mind you may be havingvisions of complex shapes being machined with little effort on your part while your twothousand-dollar investment turns out parts that the old masters of the machine tradeswould envy. Well my friend its possible, but its time to come down to earth and againthink about the complexities of doing so.
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Cutter compensationwhat makes CNC work in a machining environment

I could have sneaked out the back door and only wrote instructions for a couple of simplemoves without cutter compensation and let it go at that; but deep down inside, Id haveknown I was cheating you out of the real benefits of CNC. I believed that if I startedteaching you to use this marvelous programming tool right at the very start it will soon be

second nature, and our class will leap-frog ahead of our competition with those thickboring books being taught by instructors I wouldnt let near the least expensive CNCmachine in my shop.

If you take the effort to learn this method of programming at the start along with a littlesimple trig, youll find it well worth the effort. Cutter offsets are the way you control sizewith modern CNC machines. When you start making more complex parts and you dontuse cutter comp youll have to change the basic numbers of your programs to make a parton size. Sounds simple enough until you find that every time you correct a number hereyou end up screwing up another number there. Take my thirty-five years of experience indealing with CNC and accept this cutter offset stuff as a fact.

I cant help anyone who isnt willing to work hard

Back in ancient times the great mathematician Euclid told a Pharaoh who wanted to learngeometry the easy way that Pharaohs had to walk down the same road as scholars toeducation. In a sense Im also stating to you that you will have to learn programming thesame way as Im about to, and at this time Im only a couple of pages ahead of you. I amcertain that if I sat by the phone and answered questions twenty-four hours a day, and Idont plan to, I couldnt help those who arent willing to put forth the effort it takes ontheir own to learn to work with these marvelous tools.

Route EMC

This road that you are beginning to travel can become one of the most interesting roads

you have every traveled; however, you must take the time to gather the facts that canmake a trip so interesting. Instead of seeing great ancient cites on this road well begaining the knowledge that will make our next stop even more interesting and morecomplex. Well study a little and then apply these rules to your machine. We will firstmake simple moves that become more and more complex and at the same time moreinteresting as we travel on. Eventually we will reach Martinsville, a city on this road,where you will have so many choices as to the direction to travel that youll be leavingme and heading out on your own to design and build things that you never thoughtpossible in the past. The rules and facts that you will learn on this road will allow you tohave a machine at your control that home machinists a few short years ago couldntdream of. Take the time to enjoy this trip because youre on a road with no end if you

have set your goals correctly.

You may want to consider a CAD program in the future

Im going to close this section off by inserting something I wrote about learning andusing AutoCad. The ease with which many of the programming problems can be solvedhas to be mentioned at this time; however, I wouldnt recommend dropping what you are

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doing. From what I understand there are several excellent programs available at veryreasonable cost, but I dont want to recommend any particular program.

The following paragraph is from my book Tabletop Machining. It covers some of mycomments about learning to use a CAD program.

Learning AutoCAD

The first task I took on to learn the program was to lay out and design a set ofbevel gears that could be cut on a Sherline mill using a rotary table mounted on anangle plate. By drawing the cross sectional view accurately, the angles needed tocut this gear could be taken directly off the drawing without using a trig table or acalculator. I was beginning to see the light.

Im getting pretty good at using the program now and it has put a lot of the funback in designing for me. Looking over my partner Carls shoulder at an assemblydesigned by computer was of no help for me, and I would need a standard fullsize or larger layout to design with. Ive since found that doing the design totallymyself, it has become the perfect way for me to work. I love the program. It hasbecome the perfect program for a designer and manufacturer like myself and hasmade me more productive than ever.

Im fascinated with the program because it does a drawing without errors whenused properly. The program eliminates much of the boredom of adding andsubtracting numbers as you go. Accuracy isnt attained by the precision of yourlines but rather by the accuracy of the information the program is given. Anglesare not derived from a protractor and using divider points but from calculations bya computer to as many decimal places as needed.

I learned drafting in high school back in the fiftys. My problem was I was aslob when it came to drafting a pretty drawing. My numbers and views would

be correct, but my lettering and lines werent neat enough. Things have changednow with the aid of this program and my lettering is just as good as the best. I canno longer spill gobs of ink on an almost completed drawing and have to start over.I can change my mind as much as I want without irritating anyone. Im a happyman.

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System components: FIGURE 1.1

1) 1-5/8" manual handwheel2) Z-axis stepper motor3) Stepper motor mount4) Sherline vertical mill with standard accessories (Model 2000 mill shown)5) Backup Linux/EMC2 installation CD, Sherline instructions CD6) Y-axis stepper motor7) X-axis stepper motor8) Cable for optional A-axis (CNC rotary table) connection

9) Computer with keyboard, and mouse10) On/Off switch for stepper motor power supply11) USB drive ports (front)12) CD-RW drive13) DC spindle motor14) Included USB Flash Drive15) Power On/Off (Smaller button below is Restart button)


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FIGURE 1.2

Connections on back of your computer:

1) Keyboard connection (purple)2) Mouse connection (green)3) AC power connection4) Parallel printer port connection (from driver box)5) Internet cable connection6) Video (monitor) connection (blue)7) On/Off switch for CNC driver power supply8) Output cables to stepper motors for X-, Y-, Z-, and A-axes9) Stepper motor driver power indicator light10) 115/230V computer power supply voltage selection switch*11) 115/230V driver board voltage selection switch (inside computer case)*

12) USB ports, rear panel (more on front panel)*NOTE: Sherline attempts to ship machines with the voltage setting preset to the propervoltage for the customers location. Confirm this setting before turning the computer onfor the first time. If the setting is not correct, note that there are two switches that need tobe changed. The switch for the driver power supply is inside the computer case. ContactSherline before opening the case to change the voltage or for any reason. Breaking thetamper-proof seal without authorization may void your warranty. Illustrated instructions


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on how to locate and properly change the setting on this switch can be found atwww.sherline.com/voltage.htm.

Assembling your systemGetting your system up and running is a simple task. It consists of assembling your milland connecting it to the computer as follows:

Mill or Lathe

Unpack and assemble your machine according to the instructions included in the SherlineAssembly and Instruction Guidepacked with the machine.

Computer connections and starting up

Unpack the computer and enclosed components. Connect the stepper motor cablesleading from the back of the computer to each of the three stepper motors. A fourth cableis unused unless you have purchased an optional rotary table that can be connected hereas a 4th (A) axis. If your keyboard and/or mouse have a USB plug, insert the USB pluginto any available USB port at the back of the PC. If you have a keyboard with a purpleplug, insert it into the purple connector at the back of the PC (#1 in the previous photo). If

you have a mouse with a green plug, insert it into the green connector at the back of thePC (#2 in the previous photo). Plug your monitor to the blue video connector (6). If notalready connected, plug the free end of the 25-pin parallel cable in to the parallel port (4).Insert the female end of the power cord into its receptacle (5) in the computer and plugthe male end into a properly grounded wall socket or surge protected power strip. Makesure the computer power switch (#3) is turned on. Turn on the computer (press the powerswitch on the front of the PC) and monitor. (Note: Newer computers are powered on andstart up from a single button on the front of the case.) Leave the power switch to thestepper motors (located on the side of the PC) in the OFF position for now. Once thedesktop icons are displayed, double click the appropriate EMC2 icon.There is an EMC2icon for inch and metric versions of the CNC Mill and Lathe, so choose the

appropriate one. Wait until the EMC2 program starts up before turning on power to thestepper motors with the toggle switch on the side of the computer case.

NOTE: If you start EMC and run a program and the screen shows the program is runningbut the stepper motors are not moving, make sure both ends of the 25-pin parallel cableare plugged in as noted above. This is how the computer communicates with the driverbox and is the most common technical assistance call we get. We left the connectionexternal so that a user could unplug the driver box and plug in a printer if need be. Nowthat most printers use a USB connection, this will probably not be something you need todo unless you want to use an older printer.

Opening the instructions file on the computer

If you are not familiar with Linux, you will find the Ubuntu desktop that opens when

your computer starts up to be similar to the Windows or Mac desktop. Theinstructions for using CNC can be found on the Utilities and Instructions CD that camewith your machine. Insert the CD in the CD/DVD drive and click on the icon that appearson the desktop to show the files and folders on the disk. Double click on a PDF file toopen it. To open the HTML version, double click the file icon and then click Display inthe window that opens. Full versions of the instructions and Print (workbook) versionsare available. When done, close the instructions and right click on the DVD desktop icon
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and select Eject. We suggest you print out the shorter Print version of the instructionsto use when you are working with the examples.

Included along with the PDF and HTML versions are two MS Word (.doc) files(CNCInst5.docand CNCprint5.doc). Double clicking on a .DOC file will open it inOpenOffice on your Linux computer or in Microsoft Word if opening it on a Windows

computer. The most current version of the instructions can always be found on theInternet at http://www.sherline.com/CNCinstructions.htm. PDF and HTML files can beopened in both Linux and Windows.

Please read all the instructions before attempting to use the EMC2 program to run yourmill or lathe. CNC machining is a complicated process, and you will be directed at theproper time to run a program on the machine once you have gained the knowledge youneed to do so.

EMC2Still the latest and greatest

I chose the EMC2 program to work with because: 1) EMC uses coding standards that areused in the modern machine tool world, 2) You will not be dealing with an outdatedprogramming system, 3) EMC can deal with the cutter compensation (cutter comp) that isneeded to make complex parts in an efficient manner, 4) The cost saved by not having topay for this marvelous programming system will allow you to purchase a separatededicated computer to drive your mill, and 5) Theres great bunch of smart peopleworking on the EMC to constantly improve the system and make it easier to use in thefuture and remain current.

Basic operation of the computer and file navigation

Booting up

Before turning on the computer, make sure the 115V/230V switches on the back of the

computer and on the side of the stepper motor power supply inside the computer are setto the proper voltage for your local electrical current. The default setting is 115 VAC.Also, make sure the ON/OFF switch for the stepper motor power supply on the side ofthe computer is in the OFF (down) position. Once the EMC program is fully loadedand running, power to the stepper motors can be turned on. Do not turn on power to thestepper motors unless the EMC program is running.Controls within EMC preventoverloading of the power supply when multiple motors are powered up at the same time,but without this safeguard motors or drivers can be damaged.

Opening the EMC2 ProgramLogin and Password

When starting up, the computer will boot up without asking you to log in. If you log out

of the desktop and log back in and get a login screen, enter sherline(all lowercaseletters) for the login and sherline(all lowercase letters) for the password. Click the[Login] button and the desktop will appear.

To open EMC2, double click on the desktop icon that says either CNC Sherline BenchtopMill (inch), CNC Sherline Benchtop Mill (metric), CNC Sherline Lathe (inch)or CNCSherline Lathe (metric)depending on the machine you will be using. If the icons dontappear, move your cursor to the menu bar at the top of the screen and click on
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Applications. In the dropdown menu that appears, navigate to CNC>EMC2. In themenu tree that appears, you can select the program you need for mill or lathe, inch ormetric. Note that the program that opens from this menu tree is the Axis GUI, which isslightly different from the Mini GUI linked from the desktop icons. The differencesbetween the two are explained in the EMC User Manual which can also be found in the

Applications>CNCdropdown menu.Shutting down the computer when done

Before shutting down the computer, close all open windows and applications. Then go tothe menu bar at the top of the screen and navigate to System>Quit.After clicking onQuit, you have the choice to Log Off and leave the computer running or Turn offComputer which will log you off and shut down the computer. There is also a red powerbutton icon in the far upper right corner of the screen. Clicking on this will also offer youthe following choices: Log Off, Switch User, Lock Screen, Restart or Shut Down. (If youlog off, you will have to use the password sherline to log back in.)

Emergency stops

If you see a physical crash is about to occur, you can use the mouse and the [Feedhold]command to stop the program, remove the obstacle and then use [Continue] to continuewith the program, but that can take too much time in a panic situation. The fastest way tostop the stepper motors is to turn the power switch on the side of the computer to theOFF position. The spindle will continue to run, and the machine will have to be re-homed and the program restarted, but turning off power to the stepper motors while theyare running will not cause damage. Running a slide until it hits a hard stop should notcause any physical damage either, but power to the motor should be turned off either bystopping the program or turning the stepper motor power supply switch to OFF as soon aspossible to prevent possible overheating of the stalled motor. It might save a valuable partthat is about to be destroyed.

Transferring G-code files from another computer

1. On the computer you use to generate your G-code, save your G-code program to a CD,DVD or USB flash drive as a text (.txt) file. Program files created in EMC2 willautomatically be saved with the .ngc extension. Either file format will be recognized byEMC2.

2. Insert the CD, DVD or USB device into your Sherline Linux computer. When you do,an icon for the device will appear on your desktop. When you double click on the icon, awindow will be opened showing the contents of that device.

3. On the desktop of your Sherline Linux computer, double click on the folder named G-Code to open a new window.

4. Click on the file you wish to move, drag it from the CD, DVD or USB window andrelease the mouse button to drop it into the G-Code window. You will be offered thechoice to Move Here or Copy Here. Use the Copy Here command. A copy of thefile will now be added to the target folder and the original will remain in the sourcefolder.

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FIGURE 1.3Files are dragged and dropped in Linux the same as they are in Windows

or Mac operating systems. Above is a typical desktop with both the G-Code folder

window and the USB flash drive window open. The various EMC2 icons and G-Codefolder can be seen to the left on the desktop. In the upper left corner is the main menu

bar. The desktop background image or wallpaper can be the default or an image of

your choice.

Saving a file created or modified in EMC2 to your G-Code folder

1. On the top EMC2 menu bar, make sure the Editor box is checked (filled with color).

2. If the editor window is not displayed as the main window, click on that window tocycle through the checked functions until the window showing the lines of G-code isdisplayed.

3. The main window will now have a small menu bar above it. Select File>Save As.

When you do, a window will open.4. The default directory to save programs should be the G-Code folder. If it is not, inthe file saving window click on the file icon in the upper right corner of the window andnavigate tohome/sherline/Desktop/G-Codeto select the G-Code folder.

5. In the Name bar type in a file name and then click the [Save] button.

You can also save a file directly to a CD, DVD or USB flash drive by navigating to theappropriate drive instead of the G-Code folder (as in step 4 above) and then namingand saving as in step 5.

NOTE: In the Ubuntu version of Linux it is no longer necessary to unmount the drivewhen you are done. Simply close the drives window. If using an earlier version of linux,

you must Unmount the CD or USB device before removing it. To unmount the drive,right click on the appropriate icon on the desktop (it will have a green triangle at thebottom right corner of the icon) and select Unmount from the menu. Once the device isunmounted, the small green triangle will disappear, and you can safely remove the CD orUSB device.


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Whats in the G-Code folder?

When you open the folder called G-Code there are already several programs we havepre-loaded that you can run or modify. Here is what they are called and what they do:

0-new.ngcA blank program ready for you to open and rename to create yourown programs

TheGreatRace.ngcA triangular aircraft race course used as an example in theinstruction manual. Note: This is the only example given in the Sherlineinstructions that you dont have to type in yourself because it is lengthy for whatit does.

The following programs are written by the EMC group as examples of

different types of programming techniques and havent been fully tested by

Sherline. Ray Henry provided the explanations.

3D_Chips.ngcThis little penguin is the EMC mascot. It is written using metricdimension but can be run on any mill. It is a bit too large to run directly on the

Sherline mill but is a great sample of contouring that will go quite a ways in foam. 3dtest.ngcRuns X, Y, and Z axes to draw circles in several planes (on-screenuse only, not for cutting an actual part). Run this from near the center of each axisand it draws a circle and the letters of the plane on which the circle lies. This canbe handy when you change the angle of view of the plotter, because it will show ifyou are looking through an axis because the lettering will be backwards or upsidedown.

bbxy.ngc (Metric) This program moves the cutter in about a four-inch circle inone direction and then the other. There is an m00 between the direction change soyou need to press [Resume] or on the keyboard

bbxz.ngcbbxz.ngc is the same as bbxy above except that it makescircles in other planes.

bbyz.ngcbbyz.ngc is the same as bbxy and bbxz above except that it makescircles in other planes.

cds.ngcCircle Diamond Square (cds) is the original proof that the EMCinterpreter could run a milling machine. It is also a bit large for the Sherline millbut works great in the backplot mode. It allows you to change views and look atthe various parts of a milled cube.

diag.ngcTests movement of each axis using small incremental moves. HintYou will want to rapid to 0,0,0 before you start this program or have somethingelse to do.

skeleton.ngcA sample of code used to create a standard starting and endingcondition for a program. This does not show much if you run it but you can copyand past it into your programs and then paste your code in the center. That wayyou can be certain of the state of the machine after each run.

Dome_Test.ngcRuns X, Y and Z axes to create a slight domed surface.

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isd.ngcAs well as nist.ngc and nist2.ngc are variations of a router program thatcuts a NIST (National Institute of Standards and Technology) logo. There is anerror near the end of the code in one of them. See if you can find it. These take awhile to complete.

Opening the new file in EMC2

1. Open EMC2 by clicking on the appropriate machine icon on the desktop (CNCSherline Benchtop Mill, inch, etc.).

2. Click the [AUTO] tab along upper menu bar.

3. Click the [OPEN] tab on lower menu bar (the opened path should behome/sherline/desktop/G-Code).

4. Highlight the file you want to open by clicking on it.

5. Click the [OPEN] button.

Saving a G-code file to a CD, DVD or Flash Drive

CD or DVDThe Ubuntu version of Linux includes a free CD/DVD writing utility

called Bracero Disc Burning. Here is how to use it: Open the program by navigating the main menu toApplications>Sound &

Video>Bracero Disc Burning

Select Data Project from the four choices offered

Either drag the files to be copied into the open window from another window(such as the G-code folder) or use the navigation feature to select and include thefiles to be copied

Insert a blank CD or DVD into the drive

Click the [Burn] button in the lower right corner of the application window

Close both windows, exit the program and eject the disc.

USB Flash Drive

Insert the flash drive into an available USB port.

Click on the flash drive icon that appears on the desktop to open a window

Open the G-code folder

Drag the file(s) to be saved from the G-code folder to the flash drive window. Asmall menu will appear. Select Copy Here.

Click the X in the upper right corner of the USB drive window to close it.

Remove the drive from the USB port

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Familiarizing yourself with the control panel

The Sherline Graphical InterfaceBy Ray Henry and Joe Martin

Start your engines

After having connected everything as shown in the reference photos shown previouslyyou will need to turn on the computer but not the motor drivers (the drivers are theindividual circuitry that control the stepper motors) to see how this system runs. Thepower switch for the computer is located on the front of the computer. The driver powerswitch is located on the left side of the computer as indicated in the photo. Up is on, anddown is off.

When the computer is turned on the desktop will appear. This will allow you to haveaccess to various Linux programs; however, the only program that Sherline will be usingis one of the CNC lathe or mill, metric or inch programs. Choose the program thatrepresents the leadscrews (inch or metric) that are installed in your Sherline mill or lathe.

Double click on the appropriate desktop icon and then the EMC2 program will open.Unlike earlier versions you will not be asked for a login or password. (NOTE: If you logout and log back in you will be asked for a login and password. In machines with EMC orEMC2 installed by Sherline the login will be sherline and the password is sherline. If youhave done the installation on your own machine, the login and password will be whateveryou set up in the initial installation, so do not forget what you chose.)

I had Ray Henry put together the interface specifically for the Sherline CNC. He alsowrote much of The Sherline Graphical Interface section of the instructions. Many ofthe features of the standard EMC program were removed for the Sherline interfacebecause they didnt apply for a mill of this size and type to keep things as simple aspossible. Sherline machines do not have limit or home switches and do not have directcontrol of spindle speeds and such. It is a general motion interface to the EMC. With ityou can jog any axis. You can set coordinate systems and tools. You can verify and viewthe spindle path and motion in a built in program called Backplot and dry-run aprogram before running the machine. The panel is laid out in a sensible manner and iseasy to understand.

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FIGURE 1.4The control panel screen

The screen is laid out in sections. The first row is the menu bar across the top. Here youcan configure the screen to display additional information. The small buttons that arelocated left center of the command indicate that they control the large blank section of thecontrol panel that is sometimes called a pop-in. This will allow you to view the editor,plotter, tool page and coordinate page. If more than one pop-in is active (button shown asred) you can toggle between these pop-ins by right clicking anywhere within the pop-inscreen with your mouse.

Below the menu line is a line of control buttons. These are the primary control buttons forthe interface. Using these buttons you can change mode from [MANUAL] [AUTO][MDI] (manual data input). You can also use [FEEDHOLD] or [ABORT] to stop or aborta programmed move. When you press the [FEEDHOLD] button it changes color and

becomes a [CONTINUE] button. It toggles between running and pausing. Feedhold hasthe advantage of being able to restart the program from where you stopped it. When allelse fails press a software E-Stopthe button in the upper right labeled [ESTOP PUSH].


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There are two columns below the control line. The left side of the screen shows axisposition, feedrate override, and any messages that are sent by the EMC to the operator.You can add things like current tool number and length, type of position shown, andoffsets in effect by looking under the menu.

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in Backplot mode, keep these values in mind, as they will determine how the program isdrawn on the screen. While viewing your tool path from beneath, for example, themovements may appear to be opposite of how you have defined them in your program.

Feedhold and Feedrate Override

You can operate feedrate override and feedhold in any mode of operation. Override willchange the speed of jogs or feedrate in manual or MDI modes. A feedhold will beinitiated if you click the [FEEDHOLD] button or if you press the pause button on thekeyboard. Once in feedhold, the same actions will return you to the speed the machinewas moving before the feedhold.

You can adjust feedrate override by grabbing the slider with your mouse and dragging italong the groove. You can also change feedrate a percent at a time by clicking in thesliders groove. In auto mode you can also set feed override in 10% increments bypressing the top row of numbers on your keyboard. The number 1 will set feed rateoverride to 10 percent of programmed or jog speed. The number 9 will set 90 percent.

NOTE:Do not enter a value higher than 100 for the Feed Override, as the program willstop and you will get the error message axis 0* following error. (*The numberindicated could be 0, 1, 2 or 3 depending on the axis selected.)

Messages

The message display located under the axis positions is a sort of scratch pad for the EMC.If there are problems it will report them there. If you try to home or move an axis whenthe [ESTOP] button is pressed, youll get a message that says something aboutcommanding motion when the EMC is not ready. If an axis faults out for something likefalling behind, the message pad will show what happened.

If you want to remind yourself to change a tool for example, you can add a line of code toyour program that will display in the message box. Example: (msg, change to tool #3 andpress resume) will display change to tool #3 and press resume in the message box. Themsg, comma included is the command to make this happen; without msg, themessage wouldnt be displayed in the message box.

To erase messages, simply click the message button at the top of the pad or hold down[Alt] and press [m].

Manual Mode

Manual mode shows a set of buttons along the bottom of the right-hand column. A greenbutton labeled ALL ZERO has been added to designate the present position as thehome position. I felt that a machine of this type would be simpler to operate if it didnt

use a machine home position. This button will zero out any offsets and will home all axesright where they are.

Axis Focus (Active)

Axis focus is important in manual mode. Notice that in Figure 1 above you can see a lineor groove around the X-axis position display. This groove says that X is the active axis.It will be the target for jog moves made with the plus and minus jog buttons. You can

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are like feedhold if used this way. Once [Pause] is pressed and motion has stopped,[Step] will resume motion and continue it to the end of the current block. Press [Step]again to get the motion of the next block. Press [Resume] and the interpreter goes back toreading ahead and running the program. The combination of [Pause] and [Step] work alot like single block mode on many controllers. The difference is that [Pause] does not let

motion continue to the end of the current block.Feedrate Override and Auto Mode

The number buttons along the top of the main keyboard will change feed rate wheneveryou are in auto mode. Pressing the grav [`] gets you zero percent feed rate. One throughzero gets you ten through 100 percent feed rate. These keys can be very handy as youapproach a first cut. Move in quickly at 100 percent, throttle back to 10% and togglebetween [Feedhold] and 10% using the keyboards pause key. When you are satisfied thatyouve got it right, hit the zero to the right of nine and go.

Verify

The [Verify] button runs the interpreter through the code without initiating any motion. Ifverify finds a problem it will stop the read near the problem block and put up some sortof message. Most of the time you will be able to figure out the problem with yourprogram by reading the message given and looking in the program window at thehighlighted line. Some of the messages are not real helpful. Sometimes you will need toread a line or two ahead of the highlight to see the problem. Occasionally the messagewill refer to something well ahead of the highlight line. This often happens if you forgetto end your program with a %, m2, m30 or m60.

Restart

To the right of the program window is a space that will show a set of restart functions.These pop in whenever a program is aborted or an EStop happens while the interpreter is

running or paused. You can also display or hide these using the view menu.

Ive got to warn you that [Restart] can be risky. [Restart] reads down through theprogram to the restart line. While it does this it sets up its world model so that it canresume right where it stopped, but only if the tool is right where it was. Most of the time,when we abort or EStop its because something went wrong. Perhaps we broke a tool andwant to change it. We switch to manual mode and raise the spindle, change tools, andassuming that we got the length the same, get ready to go on. If we return the tool to thesame place where the abort was issued, the EMC will work perfectly.

It is possible to move the restart line back or ahead of where the abort happened. If youpress the [Back] or [Ahead] buttons you will see a blue highlight that shows the

relationship between the abort line and the one on which the EMC stopped. By thinkingthrough what is happening at the time of the restart you can place the tool tip where itwill resume work in an acceptable manner. You will need to think through things liketool offsets, barriers to motion along a diagonal line, and such before you press the[Restart] button. A restart is a good time to use feed rate override and the pause key onyour keyboard.

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Edit>Copycommands you can then open another program and use theEdit>Pastecommands from the menu to paste the lines of code into the new program. This editordoes not have the ability to automatically reload the program into the EMC interpreterafter a change. You will need to do that in EMC2 by selecting the file after saving it.

Backplot

[Backplot] will show the tool path that can be viewed from a chosen direction. 3-D isthe default. Other choices and controls are displayed along the top and right side of thepop-in. If you are in the middle of a cut when you press one of these control buttons themachine will pause long enough to re-compute the view.

Along the right side of Backplot is the pop-in that you can display with the [SETUP]button. This will show a small graphic that tries to show the angle you are viewing thetool path from. Below it are a series of sliders that allow you to change the angle of viewand the size of the plot. You can rotate the little position angle display with these. Theytake effect when you press the [Refresh] button. The [Reset] button removes all of thepaths from the display and readies it for a new run of the program but retains your

settings for that session.Pop-in Tool

The tool page is pretty much like the others. You can set values here and they becomeeffective when you press the [Enter] key*. You cant change tool offsets while theprogram is running or when the program is paused. The [Add Tools] and [Remove Tools]buttons work on the bottom of the tool list. Once a new tool has been added, you can useit in a program with the usual commands.

*Always use the [Enter/Return] key at the right side of the normal alpha keyboard, notthe [Enter] key at the bottom right of the numeric keypad.

Limit switchesI felt that limit switches would add an unnecessary cost to the system when using steppermotors with limited torque such as these. They have to be mounted in areas where theyare exposed to chips, oil and coolant creating more problems than they eliminate. TheSherline mill is fitted with hard stop screws on the X and Y axes that limit travel. Thesestops are the heads of cap screws fitted to the table and base and positioned to stop arunaway axis without damage. If you make a programming error that would drive thetable into a crash situation by over-traveling, the table will encounter these hard stopsbefore damaging the leadscrews and nuts.

You could also locate a home position from these hard stops by stalling the steppermotors against them. Of course you should do this in manual mode and by bringing thetable against the hard stop carefully in slow speed and "buzz" the motor against it. Ipersonally would find a differen

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